Finally, it’s good to have someone dedicated as the “game master” , someone who is not playing en who keeps track of everything. For instance, if you agree that 30 minutes per turn is the absolute maximum (should be easy), someone has to tell that “fiddler” to stop as everyone is waiting for him to finish the final placement of that single unit.
In larger games it’s possible that one guy keeps up the pace to a drag, dimishing the fun for everyone. If you agree beforehand that the pace of the game is important, the game master can talk to people about the 150-shot elf armies that will take 20-minute shooting rounds every turn. Yes, it is legal, but no because of this you cannot run this army in this battle.
The game master is also in charge of the narative including any narative rules which may or may not be balanced.
For intance, we played a massive siege @ örb wars. The 3rd edition Siege rules game the attackers a 25% point advantage, which the game master axed to ~10% because he thought that was fair. As the game master, he could make this ruling and in hindsight, he was right. The castle was an advantage, but no more than the 10% (roughly 600 points) instead of 25% (1,500 points)